I have a link where I need to specify the Jenkins logged-in User ID (if using the Build User Vars plug-in, something like $BUILD_USER_ID, but not exactly because all I care about is the user ID of the person logged into Jenkins). So: http://trac.company.com/proj/report/7?USER=$BUILD_USER_ID
is what I want to specify, so whoever the user is, I can have a sidebar link to their open Trac tickets. Can you add support in whatever way you like for me to specify the user that is logged in to Jenkins for the link?

Also, it would be nice if I could say "display this link only if a user is logged in".

Finally, could you set a default image for links? Anything is better than nothing. A nice pretty dot perhaps